2002 HD W/locking rear diff ?????

cc73101

Is it necessary to change the rear diff fluid at 3000 miles? My dealership tells me it is, or are they just looking for money? Any help would be great. I want to do the right thing.

Thanks
Mike Smith

swooshman

Hey.. I am no mechanic but I don't think it is necessary to change it that often. When the truck is new yes because the gears are new and there is going to be some wear as the gears break in and that means there will be metal build up on the magnet located in the diff. pan. After that it isn't as necessary.. I have a 94 Chev K-1500 Z71 with a locking rear end and I havn't had any problems leaving it 40,000 kms or more before any change. Now if you do a lot of riding in the water it might be necessary to take out the fill plug and check and see if the oil is grey color which means water has mixed with the diff. oil. Change it if this occurs. Also make sure that if the garage or you change the oil to use a limited slip oil, this oil has different properties in it then conventional gear oil. Good luck and I hope I was some help. If anyone else would like to comment with a little more mechanic background please feel free to help me and cc73101 out.

Swoosh Man

markbuck

you are supposed to change it after the first 500 miles.

first change is important, then you can probably go the life of the truck......

eric2001

The HD is supposed to have the rear diff fluid changed @ 500 miles towing or 5000 miles, whichever comes first. Also, if you have the Allison transmission, they recommend changing the filter @ 5000 miles, too.

I did mine a week ago @ 5300 miles. Fluid was dark, and smelled burnt, but thought fresh stuff was rather stenchy, too. I used Mobil1, with a new gasket.

BTW no magnet on diff cover, either.
-Eric

owenm1

Eric,

Where did you get the 5000 mile change info?
I changed mine around 6k after hearing some HD owners mention it. Also went with mobil 1. Old oil looked weak.
Thanks.

eric2001

I read the information on one of these boards. I think it came from the service manuals, if I recall correctly.
-Eric

lauriet1

Owenm1 - Try here:

http://www.allisontransmission.com/service/autoapp155/

There are links to download the service and maintainence information you're looking for.

eric2001

Probably more to do with the hops & barley...
The link is for the Allison filter, but I was referring to the rear diff.

BTW the stereo is a year long project (as in I start but never finish - procrastination at its finest).
-Eric

noobie1

I'm wondering where it's documented that the HD requires differential fluid change at 5000. My book only requires checking the level of front and rear at 7500. Guess who didn't change at 5000?
Anyone like to recommend a synthetic for a locking differential?

-David

eric2001

I checked through my manual, also, not stated anywhere, either. I read it somewhere (probably here in Town hall) but couldn't find it at Eaton's site, either.

I used Mobil1 synthetic gear lube (75w-90 btw) and meets GM's API service GL-5 requirement.

And just so you know, there is no need to take the cover off, there is no magnet on the diff cover to clean, so save the grief and aggrevation of scraping off the gasket and getting a new one. Just remove the drain plug, and let it drain that way.
-Eric

lauriet1

must have been my problem when I posted - Duh...the question was on the Rear Diff, NOT the transmission....sorry guys, my error. Forgot to engage the brain before the fingers. Back to the Becks now...

wtfletcher

The last truck I had (1500 Z71) recommended changing the differential fluid at 500 miles (for limited slip only). Then at the regularly scheduled intervals. I mentioned it to the dealer when I got my new truck and they said not until 50,000 (which I don't believe any longer!). For the Allison-If using non-transynd/Non-TES 295 fluid, 25,000 miles or 12 months for severe use and 50,000-24 months for regular driving. If using the transynd or tes295 it is 50,000-24 months and 100,000-48 months. Thanks to the previous post with the URL for Allison (lauriet1).
BUT, you've got a pretty expensive trans and changing it at 5,000 the 1st time isn't a bad idea! I'm changing mine at 5k. I Think I'll go ahead and use the Mobil 1 synthetic gear lube and do it myself.

markbuck

Mine was pretty much rust, pressure washed it, and sprayed with cheap Rustoleum flat black paint.

Towed TvlTrlr 1500 miles, running WFO into the wind (6.0L) in 3rd gear of 5 quite a bit last coupla weeks.

Rear diff still pretty and black. Worth a few minutes and $1 or so........

At 23k miles. Changed fluid after first tow when truck was new. Wondering when I should change again.

mcr

I looked thru my manual(2500HD, 02 with locker) and cannot find anything about changing the rear end fluid. Says to check it at intervals, but that's all. Does anyone have more written info on this?
Thanks.

gmengineman1

Our fleet experienced so much grief from the 1998 model pickups that when we ordered the last dozen new 2002 2500 HD's we decided not to spec the locking differential and when the trucks were delivered we took the to a local FWD dealer in Sacramento and had him install ARB Air_Locking units. To date, no trouble plus we now have an air compressor to perform some other tasks. (Tire inflation, etc.;. The dealer is S & H Four Wheel Drive on Arden Avenue. The cost was less than $1,200. per unit and that is cheaper in the long run than dealing with the close interval rear diff special fluid. We're satisfied that we made the correct decision.